This invention relates to a wheel assembly for a vehicle, and more specifically, the invention relates to a wheel assembly particularly useful for vehicles which frequently make tight turns.
Axle assemblies having dual wheels on either end have been used to increase the load bearing capability of heavy duty vehicles. Typically the pair of wheels on each end of the axle assembly are secured together so that they rotate together about an axis. Some heavy duty vehicles, such as lift trucks, undergo numerous turning maneuvers which wear the tires significantly. The tire wear is caused when the tires scrub, or drag, since the wheels that are secured together must travel different distances at the inside and outside of the turning radius. Sharper turns cause increased tire scrub. This problem is compounded because wheels with very large tires have a wide footprint. Different portions of the tire's footprint must travel different distances throughout the turning radius. That is, the outside of the tire must rotate a greater distance than the inside of the tire.
Tire wear and maintenance on heavy duty lift trucks due to scrub cost thousands of dollars annually per vehicle. A dual wheel assembly design has been proposed that uses hydraulic motors to independently drive each wheel. However, the design uses the operation of the suspension to reduce scrubbing and is not suitable for heavy vehicle applications. Furthermore, the hydraulic motors are not individually controlled so that the wheels cannot be rotatingly driven at different speeds relative to one another to travel along different radial distances and reduce scrubbing during vehicle turns. Therefore, what is needed is a wheel assembly with independently rotatable wheels that is also capable of reducing scrubbing across the width of each tire.